CN113939714A - Rotation speed detector - Google Patents
Rotation speed detector Download PDFInfo
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- CN113939714A CN113939714A CN201980097323.8A CN201980097323A CN113939714A CN 113939714 A CN113939714 A CN 113939714A CN 201980097323 A CN201980097323 A CN 201980097323A CN 113939714 A CN113939714 A CN 113939714A
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01D—MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR
- G01D5/00—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable
- G01D5/12—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means
- G01D5/244—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means influencing characteristics of pulses or pulse trains; generating pulses or pulse trains
- G01D5/245—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means influencing characteristics of pulses or pulse trains; generating pulses or pulse trains using a variable number of pulses in a train
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01D—MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR
- G01D5/00—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable
- G01D5/12—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means
- G01D5/14—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means influencing the magnitude of a current or voltage
- G01D5/20—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means influencing the magnitude of a current or voltage by varying inductance, e.g. by a movable armature
- G01D5/2006—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means influencing the magnitude of a current or voltage by varying inductance, e.g. by a movable armature by influencing the self-induction of one or more coils
- G01D5/2013—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means influencing the magnitude of a current or voltage by varying inductance, e.g. by a movable armature by influencing the self-induction of one or more coils by a movable ferromagnetic element, e.g. a core
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- Transmission And Conversion Of Sensor Element Output (AREA)
- Control Of Motors That Do Not Use Commutators (AREA)
Abstract
A rotational speed detector (1) is provided with: a magnet (2) attached to a shaft (4) which is a rotating body that rotates about a rotating shaft (9); and a power generation element (3) that generates an induced voltage in accordance with a change in the magnetic field caused by the rotation of the magnet (2), wherein the rotation speed detector (1) detects the rotation speed of the rotating body on the basis of the induced voltage. The power generation element (3) comprises: a magnet wire (6); a coil (7) wound between the 1 st end and the 2 nd end, which are both ends of a magnetic wire (6) among the magnetic wires (6); and ferrite beads (8) which are soft magnetic bodies and are provided in the tubular bodies at the 1 st end and the 2 nd end, respectively. The magnet (2) has a plurality of magnetic poles arranged in the direction of rotation of the magnet (2). The plurality of magnetic poles each have a1 st region and a2 nd region having different strengths of magnetic force from each other.
Description
Technical Field
The present invention relates to a rotation speed detector for detecting a rotation speed of a rotating body.
Background
A rotation speed detector is known which has a magnet attached to a rotating body and detects the rotation speed of the rotating body based on an induced voltage generated in accordance with a change in a magnetic field caused by the rotation of the magnet. Patent document 1 discloses a rotation speed detector including: a magnetic wire that undergoes magnetization reversal caused by a large barkhausen effect based on a change in a magnetic field; and a coil wound around the magnetic wire and generating an induced voltage in accordance with the magnetization reversal of the magnetic wire.
According to patent document 1, the magnet wire and the coil face the magnet in a direction perpendicular to the rotation axis of the rotating body, and thus the distance between the end portion of the magnet wire and the magnet is longer than the distance between the center portion of the magnet wire and the magnet. Therefore, the magnetic flux from the magnet is weakened at the end portions of the magnet wire as compared with the central portion of the magnet wire. Since the barkhausen effect is larger at the center of the magnetic wire than at the ends of the magnetic wire, the magnetic flux is weaker at the ends of the magnetic wire than at the center of the magnetic wire, and the generation of the induced voltage is stabilized. Thereby, the rotation speed detector can reduce fluctuation in the amount of power generation.
Patent document 1: japanese patent laid-open publication No. 2018-189426
Disclosure of Invention
According to the conventional technique of patent document 1, the magnetic flux weakens at the end portions of the magnet wires, and therefore the amount of power generation is reduced as compared with the case where the magnetic flux having the same strength as the magnetic flux acting at the center portions of the magnet wires acts on the entire magnet wires. The decrease in the amount of power generation causes a decrease in the reliability in the detection of the rotation speed, similarly to the fluctuation in the amount of power generation. As described above, according to the conventional art, it is difficult for the rotation speed detector to achieve both reduction of fluctuation of the power generation amount and suppression of reduction of the power generation amount, and it is not easy to improve the reliability of rotation speed detection.
The present invention has been made in view of the above circumstances, and an object thereof is to obtain a rotation speed detector capable of improving reliability of rotation speed detection.
In order to solve the above problems and achieve the object, a rotation speed detector according to the present invention includes: a magnet attached to a rotating body that rotates around a rotation axis; and a power generation element that generates an induced voltage in accordance with a change in the magnetic field caused by the rotation of the magnet, wherein the rotation speed detector detects the rotation speed of the rotating body based on the induced voltage. The power generation element includes: a magnetic wire; a coil wound between the 1 st end and the 2 nd end, which are both ends of a magnetic wire among the magnetic wires; and a cylindrical body which is a soft magnetic body and is provided at the 1 st end portion and the 2 nd end portion, respectively. The magnet has a plurality of magnetic poles arranged in a rotational direction of the magnet, and each of the plurality of magnetic poles has a1 st region and a2 nd region having different magnetic strengths.
ADVANTAGEOUS EFFECTS OF INVENTION
The rotation speed detector according to the present invention has an effect of improving the reliability of rotation speed detection.
Drawings
Fig. 1 is a diagram showing a rotation speed detector according to embodiment 1 of the present invention.
Fig. 2 is a plan view showing a magnet and a power generating element included in the rotation speed detector according to embodiment 1.
Fig. 3 is a diagram showing an example of a relationship between a rotation angle and a magnetic flux density of a magnet in the rotation speed detector according to embodiment 1.
Fig. 4 is a plan view showing a magnet and a power generating element included in a rotation speed detector according to embodiment 2 of the present invention.
Fig. 5 is a diagram showing an example of a relationship between a rotation angle and a magnetic flux density of a magnet in the rotation speed detector according to embodiment 2.
Fig. 6 is a diagram showing a rotation speed detector according to embodiment 3 of the present invention.
Fig. 7 is a diagram showing a rotation speed detector according to embodiment 4 of the present invention.
Fig. 8 is a plan view showing a magnet and a power generating element included in the rotation speed detector according to embodiment 4.
Fig. 9 is a diagram showing a rotation speed detector according to embodiment 5 of the present invention.
Detailed Description
The rotation speed detector according to the embodiment of the present invention will be described in detail below with reference to the drawings. The present invention is not limited to the present embodiment.
Fig. 1 is a diagram showing a rotation speed detector according to embodiment 1 of the present invention. The rotational speed detector 1 according to embodiment 1 is a magnetic rotational speed detector that detects the rotational speed of a rotating body based on an induced voltage generated in accordance with a change in a magnetization field. The rotation speed detector 1 detects the number of times the rotating body rotates.
The rotation speed detector 1 includes: a magnet 2 attached to the shaft 4; a power generating element 3 that generates an induced voltage in accordance with a change in a magnetic field caused by rotation of the magnet 2 and outputs a signal; and a processing unit 5 that processes the signal from the power generating element 3. The magnet 2 is a flat plate having a circular shape. The magnet 2 is a permanent magnet. The shaft 4 is a rotary body that rotates about a rotary shaft 9. The magnet 2 is fixed to the tip of the shaft 4 by adhesion, screw fastening, or press fitting. The shaft 4 is a drive shaft of the motor. In fig. 1, illustration of a motor main body for rotating the shaft 4 is omitted.
The processing unit 5 counts the number of pulses generated by power generation based on the signal from the power generating element 3. The processing unit 5 counts the number of pulses, thereby detecting the rotation speed of the shaft 4. Since the processing unit 5 can be operated by the induced voltage, the rotation speed can be detected without a power supply.
The power generating element 3 is disposed to face the magnet 2 in a direction parallel to the rotation axis 9. The power generating element 3 faces a surface of the magnet 2 opposite to the surface fixed to the shaft 4. The power generating element 3 may be disposed to face a surface of the magnet 2 fixed to the shaft 4 side. The power generation element 3 includes: a magnetic wire 6; a coil 7 wound around the magnet wire 6; and ferrite beads 8 provided at the 1 st end 6a and the 2 nd end 6b, which are both ends of the magnetic wire 6.
The magnet wire 6 is a magnet processed into a wire shape. The magnetic wire 6 undergoes magnetization reversal caused by the large barkhausen effect based on the change in the magnetic field. The large barkhausen effect is a phenomenon in which the magnetization direction is reversed in a short time by simultaneously moving the magnetic walls inside the magnet when the magnet is magnetized.
The coil 7 is wound between the 1 st end 6a and the 2 nd end 6 b. That is, the coil 7 is provided between the ferrite bead 8 provided at the 1 st end 6a and the ferrite bead 8 provided at the 2 nd end 6 b. The coil 7 is a magnetic pick-up coil.
The ferrite beads 8 are cylinders of soft magnetic body. The permeability of the ferrite beads 8 is higher than the permeability of the magnet wires 6. The 1 st end 6a is coated with 1 ferrite bead 8. Another 1 ferrite bead 8 is coated on the 2 nd end portion 6 b. The cylindrical bodies provided at the 1 st end 6a and the 2 nd end 6b may be soft magnetic bodies other than the ferrite beads 8, or may be cylindrical bodies made of a soft magnetic material such as iron. As the soft magnetic body, in addition to the ferrite beads 8, an iron steel material such as SS400 or S45C, a magnetic stainless steel material such as SUS430 or SUS440, or a high permeability material such as permalloy or permalloy, or the like can be used. In the power generation element 3, the wider the interval between the 2 soft magnetic bodies in the cylindrical body, the larger the magnetization reversal region of the magnetic wire 6 increases, and thus the larger the amount of power generation by the power generation element 3 becomes. Therefore, it is preferable that one of the 2 soft-magnetic cylindrical bodies is disposed at one end of the magnetic wire 6 or at a position as close as possible to the one end, and the other of the 2 soft-magnetic cylindrical bodies is disposed at the other end of the magnetic wire 6 or at a position as close as possible to the other end.
Fig. 2 is a plan view showing a magnet and a power generating element included in the rotation speed detector according to embodiment 1. Fig. 2 shows a case where the magnet 2 and the power generating element 3 are viewed from a direction parallel to the rotation axis 9 and the opposite side to the shaft 4. The power generating element 3 is disposed to face the magnet 2 at a position separated from the center of the circular shape which is the planar shape of the magnet 2. The rotation speed detector 1 is generally used in combination with an angle detector for detecting a rotation angle of a rotating body. The angle detection unit includes: a disk for optical detection, which is formed with an optical slit; a light emitting section that emits light; and a light receiving unit that detects light emitted from the light emitting unit and passing through the optical slit. For example, the disk is fixed to the rotating body on the upper surface side of the magnet 2. The light emitting section and the light receiving section are disposed at positions facing the optical slit. In fig. 1 and 2, the angle detection unit is not shown.
The magnet 2 has a plurality of magnetic poles arranged in the rotational direction of the magnet 2. In embodiment 1, the magnet 2 has 2 magnetic poles, i.e., the 1 st magnetic pole and the 2 nd magnetic pole. The 1 st magnetic pole and the 2 nd magnetic pole are 2 magnetic poles whose magnetization directions are different from each other. The magnet 2 is equally divided into a1 st magnetic pole, i.e., an N pole 2N, and a2 nd magnetic pole, i.e., an S pole 2S, with the diameter of the circle as a boundary. The magnet 2 is magnetized in a direction parallel to the rotation axis 9.
The magnet 2 is not limited to have 1 pair of N poles 2N and S poles 2S, and may have 2 or more pairs of N poles 2N and S poles 2S. That is, the magnet 2 may have 4 or more magnetic poles. The magnet 2 is not limited to a circular flat plate, and may be a cylindrical body having an opening at the center.
The N-pole 2N has 2 strongly magnetized regions Na1 and Na2 as the 1 st region and 1 weakly magnetized region Nb as the 2 nd region. The magnetization directions of the strongly magnetized regions Na1, Na2 and the weakly magnetized region Nb are the same as each other, and the intensities of the magnetic forces are different from each other. The weakly magnetized region Nb is a region having a magnetic force weaker than those of the strongly magnetized regions Na1 and Na 2. That is, the surface magnetic flux density of the weakly magnetized region Nb is smaller than the surface magnetic flux densities of the strongly magnetized regions Na1 and Na 2. The surface magnetic flux density of the strongly magnetized region Na1 and the surface magnetic flux density of the strongly magnetized region Na2 are the same.
The S pole 2S has the 1 st region, i.e., 2 strongly magnetized regions Sa1, Sa2, and the 2 nd region, i.e., 1 weakly magnetized region Sb. The magnetization directions of the strongly magnetized regions Sa1, Sa2 and the weakly magnetized region Sb are the same as each other, and the intensities of the magnetic forces are different from each other. The weak magnetization region Sb is a region having a magnetic force weaker than those of the strong magnetization regions Sa1 and Sa 2. That is, the surface magnetic flux density of the weak magnetization region Sb is smaller than the surface magnetic flux density of the strong magnetization regions Sa1, Sa 2. The surface magnetic flux density of the strongly magnetized region Sa1 is substantially the same as the surface magnetic flux density of the strongly magnetized region Sa 2. In fig. 2, the boundaries between the strongly magnetized regions Na1, Na2, Sa1, Sa2 and the weakly magnetized regions Nb, Sb are shown by solid lines.
The weakly magnetized region Nb is provided between the strongly magnetized region Na1 and the strongly magnetized region Na2 in the rotation direction. That is, weakly magnetized regions Nb are sandwiched between strongly magnetized regions Na1 and Na2 in the rotation direction. The weak magnetization region Nb is disposed at the center of the N pole 2N in the rotation direction. The weak magnetization region Sb is provided between the strong magnetization region Sa1 and the strong magnetization region Sa2 in the rotation direction. That is, the weak magnetization region Sb is sandwiched between the strong magnetization regions Sa1 and Sa2 in the rotation direction. The weak magnetization region Sb is disposed at the center of the S pole 2S in the rotation direction. The strongly magnetized region Na1 and the strongly magnetized region Sa1 are adjacent to each other in the rotation direction. The strongly magnetized region Na2 and the strongly magnetized region Sa2 are adjacent to each other in the rotation direction.
As described above, the strongly magnetized regions Na1, Na2, Sa1, Sa2 are provided at the boundary between the N pole 2N and the S pole 2S in the magnet 2. In embodiment 1, the strongly magnetized regions Na1 and Na2 and the weakly magnetized regions Nb of the N pole 2N and the strongly magnetized regions Sa1 and Sa2 and the weakly magnetized regions Sb of the S pole 2S are realized by changing the intensity of the external magnetic field applied to each region of the magnet 2 when the magnet 2 is magnetized. As a yoke core portion of a magnetizing yoke used when magnetizing the magnet 2, 2 kinds of materials having different magnetic permeability from each other are used.
In the state shown in fig. 2, the power generating element 3 faces the strongly magnetized regions Na1 and Sa 1. When the magnet 2 and the power generating element 3 are viewed in plan in a direction parallel to the rotation axis 9, the entire power generating element 3 is located in a region in which the magnetization region Na1 and the magnetization region Sa1 are added.
Fig. 3 is a diagram showing an example of a relationship between a rotation angle and a magnetic flux density of a magnet in the rotation speed detector according to embodiment 1. In fig. 3, the angle "0 degree" indicates a state in which the magnet 2 is as shown in fig. 2. The horizontal axis of the graph shown in fig. 3 indicates the rotation angle when the magnet 2 is rotated counterclockwise in fig. 2. The vertical axis of the graph shown in fig. 3 represents the magnetic flux density in the magnet wires 6.
A curve M1 shows a relationship between an angle and a magnetic flux density when the magnet 2 of embodiment 1 is rotated. A curve M2 shows the relationship between the angle and the magnetic flux density when the magnet 2 of the comparative example was rotated. The magnet 2 of the comparative example had 1 pair of N-pole and S-pole composed of only the ferromagnetic region.
In embodiment 1 and the comparative example, the direction of the magnetic flux is parallel to the longitudinal direction of the magnet wires 6 at an angle of 0 degrees. The magnetic flux density at an angle of 0 degree is maximum. When the angle is 180 degrees, the direction of the magnetic flux is opposite to that when the angle is 0 degrees. The magnetic flux density at an angle of 180 degrees is minimal.
In the case of the comparative example, the magnetic flux density was uniformly reduced in the range from around 30 degrees to around 150 degrees while the magnet 2 was rotated from 0 degrees to 180 degrees. Further, while the magnet is rotated from 180 degrees to 360 degrees, the magnetic flux density is uniformly increased in a range from about 210 degrees to about 330 degrees.
In embodiment 1, if the magnet 2 is rotated continuously from 0 degrees, the magnetic flux density decreases from the maximum value to zero in the range from about 30 degrees to about 70 degrees. The magnetic flux density is still zero in the range from about 70 degrees to about 120 degrees, and decreases from zero to a minimum value in the range from about 120 degrees to about 160 degrees. As described above, in the case of embodiment 1, the magnetic flux density decreases in a narrower angle range than in the case of the comparative example. That is, in the case of embodiment 1, the magnetic flux density abruptly changes with respect to the change in angle, as compared with the case of comparative example.
In embodiment 1, if the magnet 2 is rotated continuously from 180 degrees, the magnetic flux density increases from a minimum value to zero in a range from about 200 degrees to about 250 degrees. The magnetic flux density is zero in the range from about 250 degrees to about 300 degrees, and increases from zero to a maximum value in the range from about 300 degrees to about 340 degrees. In the case of embodiment 1, the magnetic flux density increases in a narrower angle range than in the case of the comparative example. That is, in the case of embodiment 1, the magnetic flux density abruptly changes with respect to the change in angle, as compared with the case of comparative example.
When the magnet 2 is rotated from the state shown in fig. 2, the weakly magnetized region Sb reaches a position facing the 2 nd end 6 b. Further, by rotating the magnet 2, the strongly magnetized regions Na1 and Sa1 are separated from the positions facing the power generating elements 3, and the weakly magnetized region Sb reaches the position facing the power generating elements 3. The change in magnetic flux density when the weakly magnetized region Sb passes through the position facing the power generating element 3 is smaller than the change in magnetic flux density when the strongly magnetized region Sa1 passes through the position facing the power generating element 3. Therefore, in the case of embodiment 1, the magnetic flux density does not change in an angular range including 90 degrees. Then, by further rotating the magnet 2, the weakly magnetized region Sb is separated from the position facing the power generating element 3, and the strongly magnetized regions Sa2 and Na2 reach the position facing the power generating element 3. When the magnetization regions Sa2 and Na2 reach positions facing the power generating element 3, the magnetic flux density sharply decreases from zero to a minimum value. The change in magnetic flux density when the magnet 2 rotates from 180 degrees to 360 degrees is the same as the change in magnetic flux density when the magnet 2 rotates from 0 degrees to 180 degrees, except that the magnetic flux density is different between positive and negative.
In embodiment 1, the N pole 2N and the S pole 2S of the magnet 2 are provided with the strongly magnetized regions Na1, Na2, Sa1, and Sa2 at their boundaries, whereby the angular range in which the magnetic flux density decreases and the angular range in which the magnetic flux density increases during 1 rotation of the magnet 2 are limited. In embodiment 1, magnetization reversal in the magnet wires 6 occurs in an angular range from around 120 degrees to around 160 degrees and an angular range from around 200 degrees to around 250 degrees.
As described above, in embodiment 1, the angular range in which magnetization reversal is caused can be defined as compared with the case of the comparative example. The power generating element 3 limits the angular range in which magnetization reversal occurs, and thus can suppress fluctuations in the timing at which induced voltage is output by rotation of the magnet 2. This reduces fluctuation in the timing of power generation of the power generating element 3 per rotation of the magnet 2. In addition, since the power generation element 3 changes the magnetic flux density sharply with respect to the change in angle, the amount of power generation can be increased as compared with the case of the comparative example.
In embodiment 1, the power generating element 3 and the magnet 2 face each other in a direction parallel to the rotation axis 9, and thereby the magnetic flux from the magnet 2 can act on the entire magnet wire 6. Therefore, the power generation element 3 can generate a larger amount of power than a case where only the magnetic flux acts on the center portion of the magnet wires 6.
The 1 st end portion 6a and the 2 nd end portion 6b of the magnet wire 6 are likely to have unstable changes in magnetic flux density compared to the portion of the magnet wire 6 between the 1 st end portion 6a and the 2 nd end portion 6 b. Generally, the magnet wires 6 are manufactured by cutting a wire-shaped material into a size suitable for the power generation element 3. The 1 st end portion 6a and the 2 nd end portion 6b are stressed at the time of cutting, and thus the state of the structure may change at a portion between the 1 st end portion 6a and the 2 nd end portion 6 b. The structural state may change to cause unstable change in magnetic flux density.
In embodiment 1, the ferrite beads 8 that are soft magnetic materials are coated on the 1 st end portion 6a and the 2 nd end portion 6b, and thereby the power generating element 3 guides the magnetic flux from the magnet 2 toward the 1 st end portion 6a and the magnetic flux from the magnet 2 toward the 2 nd end portion 6b to the ferrite beads 8. The ferrite bead 8 has a higher magnetic permeability than the magnetic permeability of the magnetic wire 6, and thus magnetic flux toward the 1 st end 6a and magnetic flux toward the 2 nd end 6b can be attracted to the ferrite bead 8. The power generating element 3 can apply magnetic flux to the magnet wire 6 through the ferrite bead 8 without applying magnetic flux to the 1 st end portion 6a and the 2 nd end portion 6 b. The power generation element 3 passes through the ferrite beads 8 and causes magnetic flux to act on the magnetic wires 6, thereby suppressing fluctuations in the timing of magnetization reversal caused by rotation of the magnet 2 and fluctuations in the amount of power generation. Thus, the power generating element 3 can reduce fluctuations in the timing of power generation per rotation of the magnet 2 and fluctuations in the amount of power generation per rotation of the magnet 2.
According to embodiment 1, the rotation speed detector 1 can increase the amount of power generation in the power generating element 3 and suppress fluctuations in the timing of power generation by opposing the power generating element 3 and the magnet 2 in the direction parallel to the rotation axis 9 and providing the strongly magnetized regions Na1, Na2, Sa1, Sa2 and the weakly magnetized regions Nb, Sb to the magnet 2. Further, the rotation speed detector 1 is provided with the tubular bodies of the soft magnetic bodies at both end portions of the magnetic wires 6, respectively, thereby being capable of suppressing fluctuations in the timing of power generation and fluctuations in the amount of power generation. As described above, the rotation speed detector 1 has an effect of improving the reliability of rotation speed detection.
Fig. 4 is a plan view showing a magnet and a power generating element included in a rotation speed detector according to embodiment 2 of the present invention. In the magnet 2 according to embodiment 2, weak magnetization regions Nb1, Nb2, Sb1, and Sb2 are provided at the boundary between the N pole 2N and the S pole 2S. In embodiment 2, the same components as those in embodiment 1 are denoted by the same reference numerals, and the description will be mainly given of a configuration different from that in embodiment 1. Fig. 4 shows a case where the magnet 2 and the power generating element 3 are viewed from a direction parallel to the rotation axis 9 and the opposite side to the axis 4. The magnet 2 of embodiment 2 is a cylindrical body having an opening 11 at the center. The magnet 2 may be a flat plate having a circular shape as in the case of embodiment 1.
The N-pole 2N has 1-st strongly magnetized region Na as the 1 st region and 2 weakly magnetized regions Nb1 and Nb2 as the 2 nd region. The magnetization directions of the strongly magnetized region Na and the weakly magnetized regions Nb1 and Nb2 are the same, and the intensities of the magnetic forces are different from each other. The weakly magnetized regions Nb1 and Nb2 are regions having weaker magnetic force than the strongly magnetized region Na. That is, the surface magnetic flux density of the weakly magnetized regions Nb1 and Nb2 is smaller than the surface magnetic flux density of the strongly magnetized region Na. The surface magnetic flux density of the weakly magnetized region Nb1 and the surface magnetic flux density of the weakly magnetized region Nb2 are the same.
The S pole 2S has a1 st region, i.e., a1 st strongly magnetized region Sa, and 2 nd regions, i.e., 2 weakly magnetized regions Sb1, Sb 2. The magnetization directions of the strongly magnetized region Sa and the weakly magnetized regions Sb1, Sb2 are the same, and the intensities of the magnetic forces are different from each other. The weak magnetization regions Sb1 and Sb2 are regions having a magnetic force weaker than that of the strong magnetization region Sa. That is, the surface magnetic flux density of the weak magnetization regions Sb1, Sb2 is smaller than the surface magnetic flux density of the strong magnetization region Sa. The surface magnetic flux density of the weakly magnetized region Sb1 and the surface magnetic flux density of the weakly magnetized region Sb2 are the same. In fig. 4, the boundaries between the strongly magnetized regions Na and Sa and the weakly magnetized regions Nb1, Nb2, Sb1, and Sb2 are shown by solid lines.
The strongly magnetized region Na is provided between the weakly magnetized region Nb1 and the weakly magnetized region Nb2 in the rotation direction. That is, weakly magnetized regions Nb1 and Nb2 are arranged so as to sandwich strongly magnetized region Na. The ferromagnetic region Na is disposed at the center of the N-pole 2N in the rotation direction. The strongly magnetized region Sa is provided between the weakly magnetized region Sb1 and the weakly magnetized region Sb2 in the rotation direction. That is, the weak magnetization regions Sb1 and Sb2 are disposed so as to sandwich the strong magnetization region Sa. The magnetization region Sa is disposed at the center of the S pole 2S in the rotation direction. The weakly magnetized region Nb1 and the weakly magnetized region Sb1 are adjacent to each other in the rotational direction. The weakly magnetized region Nb2 and the weakly magnetized region Sb2 are adjacent to each other in the rotational direction.
As described above, the weak magnetization regions Nb1, Nb2, Sb1, Sb2 are provided at the boundary between the N pole 2N and the S pole 2S in the magnet 2. In embodiment 2, the strong magnetization region Na and the weak magnetization regions Nb1, Nb2 of the N pole 2N and the strong magnetization region Sa and the weak magnetization regions Sb1, Sb2 of the S pole 2S are realized by changing the intensity of the external magnetic field applied to each region of the magnet 2 at the time of magnetization of the magnet 2.
In the state shown in fig. 4, the portion between the 1 st end 6a and the 2 nd end 6b of the power generating element 3 is opposed to the weak magnetization region Nb1 and the weak magnetization region Sb 1. The 1 st end 6a faces the strongly magnetized region Na. The 2 nd end portion 6b faces the strongly magnetized region Sa. The range of the strongly magnetized region Na in the rotation direction is larger than the range of the region obtained by adding the weakly magnetized region Nb1 and the weakly magnetized region Sb1 in the rotation direction and larger than the range of the region obtained by adding the weakly magnetized region Nb2 and the weakly magnetized region Sb2 in the rotation direction. The range of the strongly magnetized region Sa in the rotation direction is larger than the range of the region obtained by adding the weakly magnetized regions Nb1 and Sb1 in the rotation direction and larger than the range of the region obtained by adding the weakly magnetized regions Nb2 and Sb2 in the rotation direction.
Fig. 5 is a diagram showing an example of a relationship between a rotation angle and a magnetic flux density of a magnet in the rotation speed detector according to embodiment 2. In fig. 5, the angle "0 degree" indicates a state in which the magnet 2 is as shown in fig. 4. The horizontal axis of the graph shown in fig. 5 indicates the rotation angle when the magnet 2 is rotated counterclockwise in fig. 4. The vertical axis of the graph shown in fig. 5 represents the magnetic flux density in the magnet wires 6.
A curve M3 shows a relationship between an angle and a magnetic flux density when the magnet 2 of embodiment 2 is rotated. The curve M2 shows the relationship between the angle and the magnetic flux density when the magnet 2 of comparative example is rotated, as in the case of embodiment 1.
In the case of the comparative example, the magnetic flux density started to decrease from the maximum value in the vicinity of 30 degrees and reached to the minimum value in the vicinity of 150 degrees while the magnet 2 was rotated from 0 degrees to 180 degrees. In embodiment 2, the magnetic flux density starts decreasing from the maximum value in the vicinity of 60 degrees and reaches the minimum value in the vicinity of 120 degrees. As described above, in the case of embodiment 2, the magnetic flux density decreases in a narrower angle range than in the case of the comparative example. That is, in the case of embodiment 2, the magnetic flux density changes sharply with respect to the change in angle, as compared with the case of comparative example.
In the case of the comparative example, the magnetic flux density started to increase from the minimum value in the vicinity of 200 degrees and reached the maximum value in the vicinity of 340 degrees while the magnet 2 was rotated from 180 degrees to 360 degrees. In embodiment 2, the magnetic flux density starts increasing from a minimum value near 220 degrees and reaches a maximum value near 310 degrees. As described above, in the case of embodiment 2, the magnetic flux density increases in an angular range narrower than that in the case of the comparative example. That is, in the case of embodiment 2, the magnetic flux density changes sharply with respect to the change in angle, as compared with the case of comparative example.
When the magnet 2 is rotated from the state shown in fig. 4, the magnetized region Sa reaches a position facing the power generating element 3. Further, by rotating the magnet 2, the strongly magnetized region Sa is moved away from the position facing the power generating element 3, and the weakly magnetized regions Sb2 and Nb2 reach the position facing the power generating element 3. The range of the sum of the weakly magnetized regions Sb2 and Nb2 is smaller than the range of the strongly magnetized region Sa, and the magnetic flux density is drastically reduced. The change in magnetic flux density when the magnet 2 rotates from 180 degrees to 360 degrees is the same as the change in magnetic flux density when the magnet 2 rotates from 0 degrees to 180 degrees, except that the magnetic flux density is different in positive and negative.
In embodiment 2, weak magnetization regions Nb1, Nb2, Sb1, Sb2 are provided at the boundary between the N pole 2N and the S pole 2S in the magnet 2, whereby the angular range in which the magnetic flux density decreases and the angular range in which the magnetic flux density increases during 1 rotation of the magnet 2 are limited. As described above, in embodiment 2, the angular range in which magnetization reversal is caused can be defined as compared with the case of the comparative example. The power generating element 3 limits the angular range in which magnetization reversal occurs, and thus can suppress fluctuations in the timing at which induced voltage is output by rotation of the magnet 2. This reduces fluctuation in the timing of power generation of the power generating element 3 per rotation of the magnet 2. In addition, since the power generation element 3 changes the magnetic flux density sharply with respect to the change in angle, the amount of power generation can be increased as compared with the case of the comparative example.
According to embodiment 2, the rotation speed detector 1 can increase the amount of power generation in the power generating element 3 and suppress fluctuations in the timing of power generation by providing the strong magnetization regions Na, Sa and the weak magnetization regions Nb1, Nb2, Sb1, Sb2 in the magnet 2. This has the effect that the rotational speed detector 1 can improve the reliability of rotational speed detection.
Note that the strong magnetization regions Na1, Na2, Sa1, and Sa2 in the 1 st region of the magnet 2 of embodiment 1 and the weak magnetization regions Nb and Sb in the 2 nd region of the magnet 2 and the strong magnetization regions Na and Sa in the 1 st region and the weak magnetization regions Nb1, Nb2, Sb1, and Sb2 in the 2 nd region of the magnet 2 of embodiment 2 are not limited to those obtained by changing the intensity of the external magnetic field applied at the time of magnetization. The 1 st and 2 nd regions may be realized by the shape of the magnet 2 or the material of the magnet 2. The case where the 1 st region and the 2 nd region are realized by the shape of the magnet 2 or the material of the magnet 2 will be described in embodiment 3 and later.
Fig. 6 is a diagram showing a rotation speed detector according to embodiment 3 of the present invention. The rotation speed detector 20 according to embodiment 3 has the same configuration as the rotation speed detector 1 according to embodiment 1, except that a magnet 21 is provided instead of the magnet 2 shown in fig. 1. In embodiment 3, the same components as those in embodiments 1 and 2 are denoted by the same reference numerals, and configurations different from those in embodiments 1 and 2 will be mainly described. In fig. 6, the processing unit 5 is not shown.
In the magnet 21, the thicknesses in the direction parallel to the rotation axis 9 are different between the 1 st, i.e., strongly magnetized regions Na1, Na2, Sa1, Sa2 and the 2 nd, i.e., weakly magnetized regions Nb, Sb. The lengths of the strongly magnetized regions Na1, Na2, Sa1, and Sa2 in the magnet 21 in the direction parallel to the rotation axis 9 are longer than the lengths of the weakly magnetized regions Nb and Sb in the direction parallel to the rotation axis 9 in the magnet 21. The arrangement of the strongly magnetized regions Na1, Na2, Sa1, Sa2 and the weakly magnetized regions Nb, Sb in the magnet 21 is the same as that in the magnet 2 shown in fig. 2.
An opening 11 is provided in the center of the magnet 21. The magnet 21 is formed by deforming a cylindrical body so that the thicknesses thereof are different between the 1 st region and the 2 nd region. The magnet 21 may not be provided with the opening 11. The magnet 21 may be formed by deforming a disk so that the thicknesses in the 1 st region and the 2 nd region are different from each other.
In the magnet 21, the length in the direction parallel to the rotation axis 9 is made different for each region, thereby forming a region with a large total magnetic flux, i.e., a1 st region, and a region with a small total magnetic flux, i.e., a2 nd region. Further, since the distance between the magnet 21 and the power generating element 3 in the 1 st region is shorter than the distance between the magnet 21 and the power generating element 3 in the 2 nd region, the magnetic force acting on the power generating element 3 is stronger in the 1 st region than in the 2 nd region. The yoke core portion of the magnetizing yoke used for magnetizing the magnet 21 is flat, so that the 1 st region is in close contact with the yoke core portion, while a gap is formed between the 2 nd region and the yoke core portion. Thus, the 1 st region having a large total magnetic flux and the 2 nd region having a small total magnetic flux are formed in the magnet 21.
In embodiment 3, similarly to the case of the magnet 2 shown in fig. 4, the magnet 21 may be provided with the 1 st region, i.e., the strongly magnetized regions Na and Sa, and the 2 nd region, i.e., the weakly magnetized regions Nb1, Nb2, Sb1, and Sb 2.
Fig. 7 is a diagram showing a rotation speed detector according to embodiment 4 of the present invention. Fig. 8 is a plan view showing a magnet and a power generating element included in the rotation speed detector according to embodiment 4. The rotation speed detector 30 according to embodiment 4 has the same configuration as the rotation speed detector 1 according to embodiment 1, except that a magnet 31 is provided instead of the magnet 2 shown in fig. 1. In embodiment 4, the same components as those in embodiments 1 to 3 are denoted by the same reference numerals, and configurations different from those in embodiments 1 to 3 will be mainly described. Fig. 8 shows a case where magnet 31 and power generating element 3 are viewed from a direction parallel to rotation axis 9. In fig. 7, the processing unit 5 is not shown.
In magnet 31, the radial lengths are different between strongly magnetized regions Na1, Na2, Sa1, Sa2, which are the 1 st region, and weakly magnetized regions Nb, Sb, which are the 2 nd region. The lengths of the strongly magnetized regions Na1, Na2, Sa1, and Sa2 in the radial direction of the circle centered on the rotation axis 9 in the magnet 31 are longer than the lengths of the weakly magnetized regions Nb and Sb in the radial direction of the circle centered on the rotation axis 9 in the magnet 31. The arrangement of the strongly magnetized regions Na1, Na2, Sa1, Sa2 and the weakly magnetized regions Nb, Sb in the magnet 31 is the same as that in the magnet 2 shown in fig. 2. In fig. 8, the boundary between the N pole 2N and the S pole 2S is indicated by a solid line.
An opening 11 is provided in the center of the magnet 31. Magnet 31 is formed by deforming a cylindrical body so that the length in the radial direction is different between region 1 and region 2. Note that magnet 31 may not be provided with opening 11. The magnet 31 may be formed by deforming a disk so that the thickness in the radial direction is different between the 1 st region and the 2 nd region.
In magnet 31, the length in the radial direction is made different for each region, thereby forming a region with a large total magnetic flux, i.e., region 1, and a region with a small total magnetic flux, i.e., region 2. In embodiment 4, as in the case of the magnet 2 shown in fig. 4, the magnet 31 may be provided with the 1 st region, i.e., the strongly magnetized regions Na and Sa, and the 2 nd region, i.e., the weakly magnetized regions Nb1, Nb2, Sb1, and Sb 2.
Fig. 9 is a diagram showing a rotation speed detector according to embodiment 5 of the present invention. The rotation speed detector 40 according to embodiment 5 has the same configuration as the rotation speed detector 1 according to embodiment 1, except that a magnet 41 is provided instead of the magnet 2 shown in fig. 1. In embodiment 5, the same components as those in embodiments 1 to 4 described above are denoted by the same reference numerals, and configurations different from those in embodiments 1 to 4 will be mainly described. In fig. 9, the processing unit 5 is not shown.
The magnet 41 has a1 st portion 41a and a2 nd portion 41b, which are portions made of different materials. The 1 st portion 41a constitutes the 1 st region, i.e., the magnetized regions Na1, Na2, Sa1, and Sa 2. The 2 nd portion 41b constitutes the 2 nd region, i.e., weakly magnetized regions Nb, Sb. The material of the 1 st portion 41a has a higher residual magnetic flux density than the material of the 2 nd portion 41 b. The arrangement of the strongly magnetized regions Na1, Na2, Sa1, Sa2 and the weakly magnetized regions Nb, Sb in the magnet 41 is the same as that in the magnet 2 shown in fig. 2. The magnet 41 is a cylindrical body having an opening 11 at the center. The magnet 41 is not limited to a cylindrical body, and may be a circular plate.
In the magnet 41, a material having a higher residual magnetic flux density than that of the material of the 2 nd site 41b is used as the material of the 1 st site 41a, thereby forming a1 st region, which is a region having a large total magnetic flux, and a2 nd region, which is a region having a small total magnetic flux. In embodiment 5, similarly to the case of the magnet 2 shown in fig. 4, the magnet 41 may be provided with the 1 st region, i.e., the strongly magnetized regions Na and Sa, and the 2 nd region, i.e., the weakly magnetized regions Nb1, Nb2, Sb1, and Sb 2.
The configuration described in the above embodiment is an example of the content of the present invention, and may be combined with other known techniques, and a part of the configuration may be omitted or modified without departing from the scope of the present invention.
Description of the reference numerals
1. The device comprises a rotation speed detector 20, 30 and 40, magnets 2, 21, 31 and 41, a pole 2N N, a pole 2S S, a power generation element 3, a shaft 4, a processing part 5, a magnetic wire 6, a first end part 1 of 6a, a second end part 2 of 6b, a coil 7, a ferrite bead 8, a rotating shaft 9, an opening 11, a first part 1 of 41a, a second part 2 of 41b, a strongly magnetized area of Na, Na1, Na2, Sa1 and Sa2, and a weakly magnetized area of Nb, Nb1, Nb2, Sb1 and Sb 2.
Claims (10)
1. A rotation speed detector, comprising: a magnet attached to a rotating body that rotates around a rotation axis; and a power generation element that generates an induced voltage in accordance with a change in a magnetic field caused by rotation of the magnet, the rotation speed detector detecting a rotation speed of the rotating body based on the induced voltage,
the rotation speed detector is characterized in that,
the power generation element has: a magnetic wire; a coil wound between the 1 st end and the 2 nd end, which are both ends of the magnetic wire, of the magnetic wires; and a cylinder body which is a soft magnet and is disposed at the 1 st end portion and the 2 nd end portion, respectively,
the magnet has a plurality of magnetic poles arranged in a rotational direction of the magnet,
the plurality of magnetic poles each have a1 st region and a2 nd region having different strengths of magnetic force from each other.
2. A revolution speed detector according to claim 1,
the power generating element is opposed to the magnet in a direction parallel to the rotation axis.
3. A rotation speed detector according to claim 1 or 2,
the plurality of magnetic poles include a1 st magnetic pole and a2 nd magnetic pole having different magnetization directions from each other,
the 2 nd region is weaker in magnetic force than the 1 st region and is disposed so as to be sandwiched by the 1 st region in the rotation direction,
the 1 st region of the 1 st magnetic pole and the 1 st region of the 2 nd magnetic pole are adjacent to each other in the rotational direction.
4. A rotation speed detector according to claim 3,
when the magnet and the power generating element are viewed in plan in a direction parallel to the rotation axis in a state where the power generating element faces the 1 st region of the 1 st magnetic pole and the 1 st region of the 2 nd magnetic pole, the entire power generating element is located in a region in which the 1 st region of the 1 st magnetic pole and the 1 st region of the 2 nd magnetic pole are added.
5. A rotation speed detector according to claim 1 or 2,
the plurality of magnetic poles include a1 st magnetic pole and a2 nd magnetic pole having different magnetization directions from each other,
the 2 nd region is weaker in magnetic force than the 1 st region and is disposed so as to sandwich the 1 st region in the rotation direction,
the 2 nd region of the 1 st magnetic pole and the 2 nd region of the 2 nd magnetic pole are adjacent to each other in the rotational direction.
6. A revolution speed detector according to claim 5,
the range of the 1 st region of the 1 st magnetic pole in the rotational direction and the range of the 1 st region of the 2 nd magnetic pole in the rotational direction are each larger than the range of a region in which the 2 nd region of the 1 st magnetic pole in the rotational direction and the 2 nd region of the 2 nd magnetic pole in the rotational direction are added.
7. A rotation speed detector according to any one of claims 1 to 6,
the magnetic permeability of the barrel is higher than the magnetic permeability of the magnetic wire.
8. A rotation speed detector according to any one of claims 1 to 6,
the length of the 1 st region in the magnet in a direction parallel to the rotation axis is longer than the length of the 2 nd region in the magnet in a direction parallel to the rotation axis.
9. A rotation speed detector according to any one of claims 1 to 6,
the length of the 1 st region in the radial direction of a circle centered on the rotation axis in the magnet is longer than the length of the 2 nd region in the radial direction of a circle centered on the rotation axis in the magnet.
10. A rotation speed detector according to any one of claims 1 to 6,
as the material of the portion of the magnet constituting the 1 st region, a material having a higher residual magnetic flux density than the material of the portion of the magnet constituting the 2 nd region is used.
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| Application Number | Priority Date | Filing Date | Title |
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| PCT/JP2019/023729 WO2020250439A1 (en) | 2019-06-14 | 2019-06-14 | Rotation speed detector |
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| JP (1) | JP6647478B1 (en) |
| KR (1) | KR102446180B1 (en) |
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| JP7378586B2 (en) * | 2020-04-01 | 2023-11-13 | 三菱電機株式会社 | Power generation elements, magnetic sensors, encoders and motors using them |
| CN117203503A (en) * | 2021-04-26 | 2023-12-08 | 松下知识产权经营株式会社 | Power generating element, encoder, and method for manufacturing magnetic member |
| JP7471519B2 (en) | 2021-05-18 | 2024-04-19 | 三菱電機株式会社 | Power generation module |
| WO2024004423A1 (en) * | 2022-06-28 | 2024-01-04 | パナソニックＩｐマネジメント株式会社 | Electric power generating element, magnetic sensor, and encoder |
| WO2024084701A1 (en) * | 2022-10-21 | 2024-04-25 | 三菱電機株式会社 | Power generation element, power generation module, rotation speed detector, and power generator |
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- 2019-06-14 CN CN201980097323.8A patent/CN113939714B/en active Active
- 2019-06-14 KR KR1020217036567A patent/KR102446180B1/en active IP Right Grant
- 2019-06-14 WO PCT/JP2019/023729 patent/WO2020250439A1/en active Application Filing
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| JPWO2020250439A1 (en) | 2021-09-13 |
| JP6647478B1 (en) | 2020-02-14 |
| KR20210139475A (en) | 2021-11-22 |
| CN113939714B (en) | 2022-07-01 |
| KR102446180B1 (en) | 2022-09-23 |
| WO2020250439A1 (en) | 2020-12-17 |
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